Protective member

ABSTRACT

A protective member of flexible resilient material which is retained on the surface of a member of a fluid spring assembly to prevent the substantial accumulation of harmful abrading debris which may damage the flexible resilient spring member during the operation of the spring assembly. The protective member is particularly useful in a vehicle suspension system.

United States Patent Arthur B. Hirtreiter Akron, Ohio Apr. 14, 1969 Aug.3, 197] The Goodyear Tire & Rubber Company Akron, Ohio inventor Appi.Np. Filed Patented Assignee PROTECTIVE MEMBER 23 Claims, 7 Drawing Figs.

[1.8. CI 267/65 Int. Cl Fl6f 9/04 Field of Search 267/65, 65

[56] References Cited UNITED STATES PATENTS 2,443,433 6/1948 Sanmori267/65 (A) 3,140,880 7/1964 Masser 267/65 (A) Primary Examiner-James B.Marbert AttorneysF. W Brunner and Ronald P. Yaist ABSTRACT: A protectivemember of flexible resilient material which is retained on the surfaceof a member of a fluid spring assembly to prevent the substantialaccumulation of harmful abrading debris which may damage the flexibleresilient spring member during the operation of the spring assembly. Theprotective member is particularly useful in a vehicle suspension system.

Patented Aug. 3, 1971 3,596,395

3 Sheets-Sheet 1 INVEN'TOR. ARTHUR B.. H I RTREITER l3 ATT RNEY PatentedAug. 3, 1971 3 Sheets-Sheet 3 a J INVENTOR. ARTHUR B.HIRTREHTERPROTECTIVE MEMBER BACKGROUND OF THE INVENTION This invention relates tofluid springs, such as pneumatic or air springs of the type used influid suspension systems. More specifically, this invention relates tofluid springs of the type in which a piston member moves within theflexible resilient member of the spring to cause the compression andexpansion of the confined fluid. This invention has particularapplication to a means for preventing the accumulation of harmfulabrading debris on the surface of the piston member which may damage theflexible resilient spring member during the operation of the spring.

Pneumatic or air springs are normally employed for shock absorbing, loadsupporting, and vibration isolation in vehicle suspension systems andother industrial and military applications. In the typical fluidpressure system a flexible resilient spring member having a hollow bodyof fabric-reinforced elastomeric material, such as rubber or the like,is positioned between and attached to retaining elements to form a fluidtight chamber capable of supporting a load. Customarily, an essentiallyinextensible bead containing a circumferential retaining wire or beadring is formed at each of the peripheral ends of the member to create acompression seal on the retaining elements. The retaining elements areadapted for movement relative to each other to cause the configurationof the spring member to change with such movement, thereby resulting ina change of the pressure of the fluid contained in the chamber. Thiscompression and expansion of the column of fluid contained in thechamber occurs during what is known as the deflection cycle of thespring which includes the compression and extension or rebound strokes.

In the so-called piston-type spring, at least one of the retainingelements is a generally cylindrical piston usually made of metal whichis employed to cause the compression and expansion of the fluidcontained in the spring. In the operation of this type spring, when thepiston moves within the spring member the piston and the retainingelement attached to the other end of the spring member move relative toone another and a rolling motion is created in the toroidal loopportions of the wall of the spring member with the resulting change ofconfiguration of the spring member consequently changing the pressure ofthe fluid contained in the chamber. An excellent detailed description ofthe construction, operation, and production of the rolling lobe-type airspring, which is one of the more common piston-type springs, iscontained in Hirtreiter U. 5. Pat No. 3,043,582.

Those skilled in the art are aware that a particularly acute problemencountered during the operation of the piston type spring, forinstance, in a vehicle suspension system, is the entrapment of debris,such as road dust, tar, oil, or other foreign matter which migratesalong the outer surface of the piston during the operation of the fluidspring and becomes lodged between the outer surface of the wall of thespring member and the outer surface of the piston. Furthermore, theproblem is aggravated if the foreign matter becomes dispersed in the tarand oil which act as a binder causing the debris to stick to the surfaceof the piston and eventually harden. During the ensuing movement of theflexible spring member the accumulation of this debris eventuallyabrades the walls of the spring member and causes premature failure.

This problem is eliminated or significantly reduced by the presentinvention in which a protective member of flexible resilient material issuperposed over and made to snugly fit at least a portion of the outersurface of the piston member. The protective member is retained on thepiston member in such a manner that when the piston moves within thespring member and causes the rolling motion therein the resultingmovement of the spring member over the protective member causes a slightflexing in the protective member which deflects and/or flakes offhannful abrading debris from the surface of the piston member toeliminate any substantial accumulation of such debris. The protectivemember also provides a barrier which prevents the migration of thedebris along the outer surface of the piston during the operation of thespring.

Preferably, the protective member covers substantially the entire outerperipheral surface of the piston to most effectively prevent theaccumulation and migration of the foreign matter. However, it may alsocover only the outer peripheral surface of the end portion of the pistonthat moves within the spring member or be positioned so as to cover onlya portion of the outer peripheral surface in the central portion of thepiston.

As will become apparent, the protective members of this invention may beof various sizes, shapes, and constructions, may be manufactured from avariety of materials, and may be utilized in more than one typepneumatic pressure system.

OBJECTS OF THE INVENTION It is the principal object of this invention toincrease the operating life of a fluid spring in a fluid pressure systemby substantially reducing the accumulation of abrading debris on theouter peripheral surface of the piston member of the fluid springassembly.

It is another important object of this invention to provide in a vehiclesuspension system a pneumatic spring including a protective member tofit over at least a portion of the outer peripheral surface of thepiston member of the spring and be retained thereon in such a mannerthat when the piston member travels within the flexible spring memberthe resulting movement of the spring member over the protective membercauses a slight flexing in the protective member which deflects and/orflakes off harmful abrading debris from the surface of the piston memberand prevents the migration of such debris along the outer surfacethereof.

Other objects and advantages of this invention will become apparenthereinafter as the description thereof proceeds, the novel features,arrangements and combinations being clearly pointed out in thespecification as well as the claims thereunto appended.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view of the protective member of this invention;

FIG. 2 is an enlarged fragmentary sectional view of a modification ofthe invention shown in FIG. 1',

FIG. 3 is an elevational view shown partly in section of a typical fluidspring assembly utilizing the protective member of FIG. 1;

FIG. 4 is an enlarged fragmentary view more clearly indicating theinvention shown in FIG. 3;

FIG. 5 is a modification of the invention shown in FIG. 3 illustratinganother type of spring assembly for which the invention is useful;

FIG. 6 is a further modification of the invention shown in FIG. 3illustrating another type of spring assembly for which the invention isuseful; and

FIG. 7 is another form of the invention shown in FIG. 3 with anothermodification of the protective member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 11, one embodiment ofthe protective member 1 is shown before installation in a fluidsuspension system. The protective member 1 is generally cap-shaped,preferably assuming the contour of the piston member which it is tocover and includes a peripheral holding lip 2 at one end to providemeans for retention on the piston. The member 1 is formed in the desiredconfiguration from a flexible resilient material in any one of a numberof manners well known in the art, such as by spraying, dipping,centrifugal casting, injection molding, compression molding, or possiblyby vacuum forming. Many of the common formable polymeric materials aresuitable for this purpose as will be hereinafter discussed.

The protective member of this invention may also contain textile fabricreinforcement. This is shown in FIG. 2 in which the member 3 containsreinforcement 4 which may be in the form of cord or square woven fabriclaid on a bias, knit fabric, or even short lengths of filamentarymaterial dispersed in the flexible material of the member.

FlGS. 3 and 4 shown a typical application for the protective member 1 ina fluid pressure system, which in this instance is a combination bellowsand piston-type spring assembly 5 which, for instance, is used in avehicle suspension system. The spring 5 is shown under load in a normalor design position. As illustrated, the spring assembly 5 includes aflexible resilient spring member 6 having a hollow body of fabric-reinforced elastomeric material, such as rubber or the like. The upperportion of the spring member 6 is in the form of a bellows lobe 7 ofgenerally toroidal-shape and the lower portion is in the form of thetypical rolling lobe tubular sleeve or toroidal loop 8. The springmember 6 is installed in the system in the customary manner by havingone of its peripheral ends attached to a relatively rigid metal pistonassembly 9 which serves as a lower retaining element and includes agenerally cylindrical modified bell-shaped piston 10 and the otherperipheral end attached to an upper retaining element 11 spaced from the1 the vehicle frame. A metal retaining ring 15, commonly referred to asa girdle ring, holds the central portion of the spring member 6 in placeduring the operation of the spring 5.

When the piston member 10 travels within the spring member 6, the pistonassembly 9 and the upper retaining element 1] move relative to eachother and change the configuration of the spring member 6 by creating arolling motion in the toroidal loop 8 or so-called rolling lobe portionof the wall of the spring member 6 in the direction of the movement,which is shown in broken lines. The column of air or other fluidcontained in the chamber of the spring member 6 is compressed andexpanded by the reciprocating action of the piston member 10 and therebyis able to support a load, such as a vehicle body.

The protective member 1 is superposed over and made to snugly fit atleast the outer peripheral surface of the piston member 10 that travelswithin the spring member 6 during the operation of the spring 5. Theprotective member 1 is retained on the piston 10, for example, by beingheld securely between the bead 12 of the spring member 6 and the pistonmem ber 10 by means of the peripheral holding lip 2. This is mostclearly shown in FIG. 4.

Since the protective member 1 is not adhered completely to the outerperipheral surface of the piston member 10, it is free to move or flexduring the operation of the spring 5. Consequently, when the pistonmember 10 travels within the spring member 6 during the compressionstroke a rolling motion is caused in the toroidal loop portion 8 of themember 6 and the resulting movement of the spring member 6 over theprotective member 1 causes a slight flexing in the protective member 1,which is shown in broken lines in FIG. 4. This movement or flexing actsto deflect and/or flake off harmful abrading debris 16 from the surfaceof the piston member 10 to eliminate any substantial accumulation ofsuch debris 16. In addition, the protective member 1 also provides abarrier to prevent the migration of such debris 16 along the outersurface of the piston member 10 during the operation of the fluidpressure system.

Of course, the protective member of this invention may be used in anynumber of fluid pressure systems and in conjunction with any size orshape piston with the member produced to assume the particular pistonconfiguration. For instance, as

shown in FIG. 5, the protective member 17 may be used in the typicalrolling lobe air spring assembly 18 to cover a straightwalled pistonmember 19. The spring assembly 18 is shown in the normal operating ordesign position during the operation of the system. In this arrangementthe flexible spring member 20 is in the form of a generally cylindricalsleeve. The operation of this type spring is basically identical to thatof the combination bellows and rolling lobe air spring as previouslydescribed and shown in FIGS. 3 and 4. Also, the protective member may beused in a system as shown in FIG. 6 in which the spaced retainingelements are bell-shaped pistons 21 and 22 which act at opposite ends ofthe flexible spring member 23 and the protective member 24 may be placedover either or both pistons 21 and 22. This system is also shown in thedesign position while under compression.

In order that the necessary flexing occurs in the protective member asit comes in contact with the spring member, it is necessary that thethickness or gauge of the protective member be controlled duringmanufacture. lt has been found that a thickness range of from about0.030 of an inch to about 0.375 of an inch produces the mostsatisfactory results with a preferred range of from about 0.060 of aninch to about 0.250 of an inch being most appropriate when theprotective member is retained in the manner shown in FIGS. 3 and 4. Inaddition to this means of retention, the member may also for instance becemented to either the top or bottom of the piston member. When thethickness of the member is in excess of about 0.090 inch the member maybe retained on the outer surface of the piston member by being adheredcompletely thereto in any manner well known in the art. This is truesince, because of the added thickness, the member is able to flexsufficiently even though bonded to the surface of the piston.

Preferably, the protective member is in the form of a cap or bootcovering substantially the entire outer peripheral surface of the pistonmember as is shown in FIGS. 3 through 6. In this way road dust and otherforeign particles are largely prevented from migrating along the surfaceof the piston at the point most remote from the spring member therebydecreasing the possibility of eventual entrapment and accumulation whichdamages the wall of the spring member. However, the protective memberwill be effective in preventing or substantially reducing the harmfulaccumulation of abrading debris if placed in other locations on theouter surface of the piston as well. For example, the protective membermay only cover the end portion of the piston member that travels withthe spring member during the operation of the fluid pressure system.

In FIG. 7 an alternative form of the invention is shown in which theprotective member 25 is in the form of a band of flexible resilientmaterial which covers only the central portion 26 of the outerperipheral surface of the piston member 27. In this arrangement theprotective member 25 may be retained on the piston member 27 by bondingif of sufflcient thickness as previously discussed or may be retained insome other manner, for instance, by means of fasteners formed on thesurface of the protective member during manufacture or by means of aspecially constructed piston adapted for receiving the protectivemember.

The protective members of this invention may be manufactured from any ofthe well-known polymeric materials, such as of natural rubber, syntheticrubber, and polyvinyl chloride. Preferably, the polymeric materialshould exhibit high abrasion and tear resistance and should also be ofrelatively low modulus so that the normal motion or movement of thespring member will cause the protective member to move in relation tothe piston. For example, in this regard it has been determined that whena force of from about 5 to about 60 pounds is exerted on a one-inchsection of the protective member a displacement or movement therein offrom about 10 to about 20 percent should result. The most satisfactoryresults are attained when a force of from about 10 to about 40 pounds isrequired to achieve the desired percent displacement. Polyurethaneelastomers and polyvinyl chloride are particularly suitable materialsfor this application.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in the art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What I claim is:

l. A protective member of flexible resilient material superposed overand snugly fitting at least a portion of the outer peripheral surface ofa generally cylindrical relatively rigid piston member of a fluidpressure system, such system being of the type in which one of theperipheral end portions of a flexible resilient hollow spring member isattached to the piston member and the other end portion is attached to aspaced retaining element to form a fluidtight chamber capable ofsupporting a load, the piston member and retaining element being movablewith respect to each other to cause a change in the configuration of thespring member and in the pressure of the fluid contained in the chamber,said piston member moving within said spring member to cause a rollingmotion therein, said protective member being retained on said pistonmember in such a manner that when the piston member travels within saidspring member to cause the rolling motion therein the resulting movementof said spring member over said protective member causes a slightflexing in said protective member which deflects and/or flakes offharmful abrading debris from the surface of the piston member toeliminate any substantial accumulation of such debris and also providesa barrier to prevent the migration of such debris along the outersurface of said piston member during the operation of the fluid pressuresystem.

2. The protective member as claimed in claim 1 wherein said protectivemember covers at least the outer peripheral surface of the end portionof said piston member that travels within said spring member during theoperation of the fluid pressure system.

3. The protective member as claimed in claim 1 wherein said protectivemember covers at least the central portion of the outer peripheralsurface of said piston member.

4. The protective member as claimed in claim 1 wherein said protectivemember covers substantially the entire outer peripheral surface of saidpiston member.

5. The protective member as claimed in claim 1 wherein the thickness ofsaid protective member is from about 0.030 of an inch to about 0.375 ofan inch.

6. The protective member as claimed in claim 1 wherein the thickness ofsaid protective member is from about 0.060 of an inch to about 0.250 ofan inch.

7. The protective member as claimed in claim 1 wherein said protectivemember is retained on the outer peripheral surface of the end portion ofsaid piston member that moves within said spring member during theoperation of the fluid pressure system.

8. The protective member as claimed in claim 1 wherein the thickness ofsaid protective member is greater than 0.090 inch and said protectivemember is adhered to the outer peripheral surface of said piston member.

9. The protective member as claimed in claim 1 wherein the protectivemember includes a textile fabric reinforcement therein.

10. The protective member as claimed in claim 1 wherein the flexibleresilient material is polymeric material of relatively low modulus andis selected from the group consisting of natural rubber, syntheticrubber, and polyvinyl chloride.

11. The protective member as claimed in claim 1 wherein the flexibleresilient polymeric material is selected from the group consisting ofpolyurethane elastomers and polyvinyl chloride.

11.2. in a fluid pressure system including A. a flexible resilienthollow spring member;

B. a pair of spaced retaining elements with each being attached to aperipheral end portion of said spring member to form a fluid tightchamber capable of supporting a load with said elements being movablerelative to each other to cause a change In he configuration of thespring member and in the pressure of the fluid in the chamber, at leastone of said elements being a generally cylindrical relatively rigidpiston member which moves within said spring member to cause a rollingmotion therein; and

C. the improvement comprising a protective member of flexible resilientmaterial superposed over and snugly fitting at least a portion of theouter peripheral surface of said piston member and retained thereon insuch a manner that when the piston member travels within said springmember to cause the rolling motion therein, the resulting movement ofsaid spring member over said protective member causes a slight flexingin said protective member which deflects and/or flakes off harmfulabrading debris from the surface of the piston member to eliminate anysubstantial accumulation of such debris and also provides a barrier tothe migration of such debris along the outer surface of said pistonduring the operation of the fluid pressure system.

13. The system as claimed in claim 12 wherein each said retainingelement comprises a generally cylindrical relatively rigid piston memberand one said protective member is retained on each said piston member.

M. The protective member as claimed in claim 12 wherein said protectivemember covers at least the outer peripheral surface of the end portionof said piston member that moves within said spring member during theoperation of the fluid pressure system.

15. The protective member as claimed in claim 12 wherein said protectivemember covers at least the central portion of the outer peripheralsurface of said piston member.

to. The protective member as claimed in claim 12 wherein said protectivemember covers substantially the entire outer peripheral surface of saidpiston member.

17. The protective member as claimed in claim 12 wherein the thicknessof said protective member is from about 0.030 of an inch to about 0.375of an inch.

18. The protective member as claimed in claim 12 wherein the thicknessof said protective member is from about 0.060 of an inch to about 0.250of an inch.

19. The protective member as claimed in claim 12 wherein said protectivemember is retained on the outer peripheral surface of the end portion ofsaid piston member that moves within said spring member during theoperation of the fluid pressure system.

20. The protective member as claimed in claim 12 wherein the thicknessof said protective member is greater than 0.090 of an inch and saidprotective member is adhered to the outer peripheral surface of saidpiston member.

211. The protective member as claimed in claim 12 wherein the protectivemember includes a textile fabric reinforcement therein.

22. The protective member as claimed in claim 12 wherein the flexibleresilient material is polymeric material of relatively low modulus andselected from the group consisting of natural rubber, synthetic rubber,and polyvinyl chloride.

23. The protective member as claimed in claim 12 wherein the flexibleresilient polymeric material is selected from the group consisting ofpolyurethane elastomers and polyvinyl chloride.

1. A protective member of flexible resilient material superposed overand snugly fitting at least a portion of the outer peripheral surface ofa generally cylindrical relatively rigid piston member of a fluidpressure system, such system being of the type in which one of theperipheral end portions of a flexible resilient hollow spring member isattached to the piston member and the other end portion is attached to aspaced retaining element to form a fluidtight chamber capable ofsupporting a load, the piston member and retaining element being movablewith respect to each other to cause a change in the configuration of thespring member and in the pressure of the fluid contained in the chamber,said piston member moving within said spring member to cause a rollingmotion therein, said protective member being retained on said pistonmember in such a manner that when the piston member travels within saidspring member to cause the rolling motion therein the resulting movementof said spring member over said protective member causes a slightflexing in said protective member which deflects and/or flakes offharmful abrading debris from the surface of the piston member toeliminate any substantial accumulation of such debris and also providesa barrier to prevent the migration of such debris along the outersurface of said piston member during the operation of the fluid pressuresystem.
 2. The protective member as claimed in claim 1 wherein saidprotective member covers at least the outer peripheral surface of theend portion of said piston member that travels within said spring memberduring the operation of the fluid pressure system.
 3. The protectivemember as claimed in claim 1 wherein said protective member covers atleast the central portion of the outer peripheral surface of said pistonmember.
 4. The protective member as claimed in claim 1 wherein saidprotective member covers substantially the entire outer peripheralsurface of said piston member.
 5. The protective member as claimed inclaim 1 wherein the thickness of said protective member is from about0.030 of an inch to about 0.375 of an inch.
 6. The protective member asclaimed in claim 1 wherein the thickness of said protective member isfrom about 0.060 of an inch to about 0.250 of an inch.
 7. The protectivemember as claimed in claim 1 wherein said protective member is retainEdon the outer peripheral surface of the end portion of said piston memberthat moves within said spring member during the operation of the fluidpressure system.
 8. The protective member as claimed in claim 1 whereinthe thickness of said protective member is greater than 0.090 inch andsaid protective member is adhered to the outer peripheral surface ofsaid piston member.
 9. The protective member as claimed in claim 1wherein the protective member includes a textile fabric reinforcementtherein.
 10. The protective member as claimed in claim 1 wherein theflexible resilient material is polymeric material of relatively lowmodulus and is selected from the group consisting of natural rubber,synthetic rubber, and polyvinyl chloride.
 11. The protective member asclaimed in claim 1 wherein the flexible resilient polymeric material isselected from the group consisting of polyurethane elastomers andpolyvinyl chloride.
 12. In a fluid pressure system including A. aflexible resilient hollow spring member; B. a pair of spaced retainingelements with each being attached to a peripheral end portion of saidspring member to form a fluid tight chamber capable of supporting a loadwith said elements being movable relative to each other to cause achange in the configuration of the spring member and in the pressure ofthe fluid in the chamber, at least one of said elements being agenerally cylindrical relatively rigid piston member which moves withinsaid spring member to cause a rolling motion therein; and C. theimprovement comprising a protective member of flexible resilientmaterial superposed over and snugly fitting at least a portion of theouter peripheral surface of said piston member and retained thereon insuch a manner that when the piston member travels within said springmember to cause the rolling motion therein, the resulting movement ofsaid spring member over said protective member causes a slight flexingin said protective member which deflects and/or flakes off harmfulabrading debris from the surface of the piston member to eliminate anysubstantial accumulation of such debris and also provides a barrier tothe migration of such debris along the outer surface of said pistonduring the operation of the fluid pressure system.
 13. The system asclaimed in claim 12 wherein each said retaining element comprises agenerally cylindrical relatively rigid piston member and one saidprotective member is retained on each said piston member.
 14. Theprotective member as claimed in claim 12 wherein said protective membercovers at least the outer peripheral surface of the end portion of saidpiston member that moves within said spring member during the operationof the fluid pressure system.
 15. The protective member as claimed inclaim 12 wherein said protective member covers at least the centralportion of the outer peripheral surface of said piston member.
 16. Theprotective member as claimed in claim 12 wherein said protective membercovers substantially the entire outer peripheral surface of said pistonmember.
 17. The protective member as claimed in claim 12 wherein thethickness of said protective member is from about 0.030 of an inch toabout 0.375 of an inch.
 18. The protective member as claimed in claim 12wherein the thickness of said protective member is from about 0.060 ofan inch to about 0.250 of an inch.
 19. The protective member as claimedin claim 12 wherein said protective member is retained on the outerperipheral surface of the end portion of said piston member that moveswithin said spring member during the operation of the fluid pressuresystem.
 20. The protective member as claimed in claim 12 wherein thethickness of said protective member is greater than 0.090 of an inch andsaid protective member is adhered to the outer peripheral surface ofsaid piston member.
 21. The protective member as claimed in claim 12wherein the protective member includes a textile fabRic reinforcementtherein.
 22. The protective member as claimed in claim 12 wherein theflexible resilient material is polymeric material of relatively lowmodulus and selected from the group consisting of natural rubber,synthetic rubber, and polyvinyl chloride.
 23. The protective member asclaimed in claim 12 wherein the flexible resilient polymeric material isselected from the group consisting of polyurethane elastomers andpolyvinyl chloride.